A man in prison asked a newcomer why he was sent there.
The newcomer answered, "Just bad luck, I suppose. A few days ago, I was walking down the street when I saw a piece of dirty rope. Thinking nobody wanted it, I picked it up and took it home."
"But picking up a piece of rope isn't against the law!" the first man exclaimed.
"I told you it was bad luck, didn't I?" the newcomer sighed. "The trouble was, I didn't notice there was an ox at the other end of that rope."